An investigator for Europe’s leading human rights watchdog accused America yesterday of “gangster tactics” in its war on terrorism, notably the illegal transfer of terrorist suspects to countries likely to torture them.

Dick Marty, a Swiss senator, told the Council of Europe that the US, with European complicity, had shipped possibly more than 100 suspects to countries where they faced torture.

“The entire continent is involved,” Mr Marty told its parliamentary assembly. He presented colleagues with an interim report dominated by newspaper cuttings and buttressed with evidence from an Italian inquiry into the alleged 2003 kidnapping by the CIA of a radical Egyptian cleric, Osama Moustafa Hassan Nasr, in Milan.

Mr Marty said it was “highly unlikely that European governments, or at least their intelligence services, were unaware” of such abductions. He accused Britain of particular complicity on the basis of a leaked secret memo from Sir Michael Wood, the chief legal adviser to the Foreign Office. In the 2003 memo Sir Michael asserted that there was no legal barrier to using foreign intelligence obtained under torture.

The document was handed to Mr Marty and the Council of Europe by Craig Murray, a former British ambassador to Uzbekistan who has become a fierce critic of British foreign policy. Giving evidence to the Strasbourg assembly, he said that, as envoy in Tashkent after September 11, 2001, he read CIA intelligence, shared with MI6, derived from torture sessions.

Later he said Britain was “much more deeply implicated” than other European nations in CIA extraordinary renditions, or the transfer of detainees outside normal judicial channels.

Several British members of the assembly, which gathers MPs from 46 countries, criticised Mr Marty’s report.

Michael Hancock, a Liberal Democrat, said it needed to have “more substance. . . many of the issues are clouded in myth and a desire to kick America.” Denis MacShane, the former Europe minister, said the report had “more holes than a Swiss cheese”.

The Council of Europe, which is independent of the European Union, was set up in 1949 as a guardian of human rights in Europe.